Lubricating oil compositions containing nu-dialkylaminoalkyl alkenyl succinimides



United States Patent Oflice LUBRICATING OIL COMPOSITIONS CONTAININGN-DIALKYLAMINOALKYL ALKENYL SUCCIN- IMIDES Robert G. Anderson, Novato,Frank A. Stuart, Orinda, and Alan Y. Drnmmond, Richmond, Calif.,assignors to California Research Corporation, San Francisco, Calif., acorporation of Delaware No Drawing. Filed Aug. 24, 1959, Ser. No.835,390

8 Claims. (Cl. 252-515) This invention pertains to lubricating oilcompositions containing N-dialkylaminoalkyl alkenyl succinimides asdetergents.

Alkenyl succinic anhydrides and numerous derivatives thereof are wellknown in the art. For example, alkenyl succinic anhydrides in which thealkenyl radical contains from to 20 carbon atoms are taught as corrosionin hibitors in lubricating compositions. Also, products obtained byreacting such alkenyl succinic anhydrides with monoamines are taught asferrous corrosion inhibitors for lubricating oil compositions.

However, the above known alkenyl succinimides are not useful asdetergents for lubricating oil compositions. In contrast thereto, thealkenyl succinimides described herein are useful as detergents inlubricating oil compositions.

Present clay internal combustion engines operate at high speeds and highcompression ratios. When used in the so-called city stop-and-go driving,which includes the greater part of the driving condition for a largepercentage of todays automobiles, the internal combustion engin es donot reach the most efficient operating temperature. Under. city drivingconditions, large amounts of particle oxidation products are formed, andreach the crankcase of the engine by blowing past the piston rings. Mostof these partial oxidation products are oil insoluble, tending to formdeposits on the various operating parts of the engine, such as thepistons, piston rings, etc. For the purpose of preventing the depositionof these products on the various engine parts, it is necessary toincorporate detergents in the lubricating oil compositions, thus keepingthese polymeric products highly dispersed in a condition unfavorable fordeposition on metals.

For the most part, the various detergents which are fectiveness asdetergents for dispersing the precursors of sludges and varnishes aremetal organic compounds, particularly those compounds wherein the metalis linked to an organic group through an oxygen atom. Although thesemetal-containing organic compounds have some effectiveness as detergentsfor dispersing the precursors of deposits within the oil itself ratherthan permitting them to form added deposits on the engine parts, theyhave the disadvantage of forming ash deposits in the engine. These ashdeposits lower engine performance by fouling the spark plugs and valvesand contributing to preignition.

It is a particular object of this invention to set forth lubricting oilcompositions containing new compounds which are particularly useful asmetal-free detergents.

Therefore, in accordance with this invention, it has been discoveredthat lubricating oil compositions particularly useful for heavy dutyservice are obtained by intaining-these alkenyl succinimides, dieseland-gasoline engine parts remain remarkably free of deposits and varnisheven under severe operating conditions.

The N-dialkylaminoalkyl monoalkenyl succinimides wherein the alkenylradical contains from 30 to 200 carbon atoms, and wherein saiddialkylaminoalkyl radical contains a total of 3 to 10 carbon atoms, canbe represented by the formula:

wherein R is an alkenyl radical containing from 30 to 200 carbon atoms,R is a divalent alkylene radical, and R and R are alkyl radicals. Thesum of the carbon atoms in the R, R and R is from 3 to 10; that is, R,

R and R contain a total of no more than 10 carbon atoms.

It is particularly preferred that R is a polymer of an" olefincontaining from 2 to 5 carbon atoms, wherein the polymer has a molecularweight from 400 to 3000, more particularly from about 900 to about 1200.Such olefins are exemplified by ethylene, propylene, l-buteue, 2-butene,isobutene, and mixtures thereof. Since the methods of polymerizing theolefins to form polymers thereof is immaterial in the formation of thenew compound described herein, any of the numerous processes availablecan be used therefor.

R' alkylene radicals include the divalent ethylene radical, propyleneradical, butylene radical, etc. R and R alkyl radicals include methyl,ethyl, propyl, etc. It is particularly preferred that R' contains 3carbon atoms, and that R and R each contain 1 carbon atom.

Amine reactants for the formation of N-dialkylaminoalkyl alkenylsuccinimidesinclhded dimethylarninomethylamine, dimethylaminoethylamine,dimethylaminopropylamine, dimethylaminobutylamine,dimethylaminoheptylamine, diethylaminomethylamine,diethylaminopropylamine, diethylaminoamylamine,dipropylaminopropylamine, methylpropylaminoamylamine,propylbutylaminoethylamine, etc.

The preparation of the monoalkenyl succinimides herein can be describedgenerally by the following equations, wherein a polyolefin is reactedwith maleic anhydride to form a monoalkenyl succinic anhydride, which,in turn, is then reacted with a dialkylaminoalkylamine to form anN-dialkylaminoalkyl monoalkenyl succinimide. Using a polymer ofisobutene as an example of the alkenyl radical, anddimethylaminopropylamine to exemplify the dialkylaminoalkylamine, theseequations are as follows:

Patented Jan. 23, 1962 Y The above reaction between a polyolefin andmaleic anhydride is an uncatalyzed addition reaction which should not beconfused with a copolymerization reaction such as that obtained with avinyl monomer and maleic anhydride. While the general reaction of anolefin and maleic anhydride is well known for olefins of low molecularweight (e.g., olefins of 18 carbon atoms), no previous work has beendone with maleic anhydride and the high molecular weight olefins asdescribed herein.

In the second step of the reaction as exemplified in Equation 11hereinabove, the reactants are used in such proportions and the reactionconditions are such that an imide is formed, not a diamide.

The reaction set forth and described by Equation I hereinabove canproceed in a mol ratio of the polyolefin to the 'maleic anhydride of 1:1to 1:10; preferably from 1:1 to 1:5. The reaction temperature can varyfrom 300 F. to 450 F. Because of the greater yield obtained thereby, itis preferred to use the higher temperature range (e.g., 375 F. to 450F.).

In the second step of the reaction as exemplified by Equation Hhereinabove, the yield of the imide is extremely high even though thereactants are used in equal molar ratios.

The reaction described by Equation 11 hereinabove can be made at 220 F.to 500 F., preferably from 300 F. to 400 F. The alkenyl succinicanhydride and the polyamine are reacted in about equal molar quantities.An excess of amine can be used, and the unreacted amine removed bydistillation.

Since the reaction between the polyolefin and maleic anhydride may notgo to completion, the resulting alkenyl succinic anhydride may containsome unreactedpolyolefin. As it may not be desirable to separate outthis unreacted polyolefin at this stage, the resulting imide formed byreaction of the alkenyl succinic anhydride and the diamine will containthis polyolefin as an impurity which can be a diluent in the formationof lubricating oil compositions. However, if it is so desired, thisunreacted polyolefin can be removed by precipitation, for example, byaceton or methanol from a hydrocarbon solution.

The preparation of N-dialkylaminoalkyl monoalkenyl succinimides isillustrated in the following examples.

Example I.-Preparatin of polybutenyl succinic anhydride A mixture of1000 grams (1 mol) of a polybutene having a molecular weight of about1000 and 98 grams (1 mol) of maleic anhydride was heatedat 410 F. in anitrogen atmosphere with agitation for a period of 24 hours. Thereaction mixture was cooled to 150 F., and 700 cc. of hexane added;after which the mixture was filtered under vacuum. After vacuumdistillation to remove the hexane from the filtrate, the product wasmaintained at 350 F. at an absolute pressure of mm. Hg for one hour toremove traces of maleic anhydride. The crude polybutenyl succinicanhydride thus prepared had a saponification number of 79.

Example II.-Preparation of N-dimethylaminopmpyl polybutenyl succinimideA mixture of 21.3 grams (0.21 mol) of dimethyl- CH: C H! H CH --CH:CH:CCH3 NCHICH CHPN Hr-C I aminopropylamine and 150 grams (0.09 mol) of thepolybutenyl succinic anhydride of Example I hereinabove, was blendedwith agitation in a nitrogen atmosphere, and the mixture was heated at500 F. for a period of one hour, after which the absolute pressure wasreduced to about 200 mm. Hg at this temperature during a period of 30minutes to facilitate the removal of water and excess amine. Thereaction mixture was then allowed to reach room temperature at thisreduced pressure. The reaction product contained 1.7% nitrogen (theory:1.8%). The identity of the N-dimethylaminopropylalkenyl succinimide wasestablished by means of infrared spectroscopy.

Table I hereinbelow presents further data concerning the preparation ofN-dialkylaminoalkyl alkenyl succinimides. The polyamine wasdimethylaminopropylamine, and the alkenyl radical on the alkenylsuccinimide was a polybutene, the molecular weight of which is noted inTable 'I.

1 Polyisobutenyl succinic anhydride.

As lubricating oil additives, these alkenyl 'succinimides can be used inamounts'of 0.1% to by weight, preferably 0.25% to 5%, by weight.

Lubricating oils which can be used as base oils for lubricating oilcompositions of such alkenyl succinimides include a wide variety oflubricating oils, such as naphthenic base, paraflin base, and mixed baselubricating oils, other hydrocarbon lubricants, e.g., lubricating oilsderived from coal products, and synthetic oils, e.g., alkylene polymers(such as polymers of propylene, butylene, etc., and the mixturesthereof), alkylene oxide-type polymers (e.g., alkylene oxide polymersprepared by polymerizing the alkylene oxide, e.g., propylene oxide,etc., in the presence of water or alcohols, e.g., ethylene alcohol),dicarboxylic acid esters (e.g., those which are prepared by esterifyingsuch dicarboxylic acids as adipic acid, azelaic acid, suberic acid,sebacic acid, alkanol succinic acid, fumaric acid, maleic acid, etc.,with alcohols, such as butyl alcohol, hexyl alcohol, Z-ethylhexylalcohol, dodecyl alcohol, etc.), liquid esters of acids of phosphorus,alkyl benzenes, polyphenyls-(e.g., biphenyls and terphenyls), alkylbiphenyl ethers, polymers-of silicon (e.g., tetraethyl silicate,tetraisopropyl silicates, tetra (4- methyl-Z-tetraethyl) silicate, hexyl(4-methyl-2-pentoxy) disiloxane,'poly(methyl) siloxane, andpoly(methylphenyl) siloxane), etc.

The above base oils may be used individually or in combinations thereof,wherever miscible or wherever made so by the use of mutual solvents.

Table II hereinbelow sets forth data showing the dicetiveness ofN-dialkylaminoalkyl monoalkenyl succinimides as lubricating oiladditives.

The succinimide used was an N-dimethylaminopropyl alkenyl succinimidewherein the alkenyl radical had a molecular weight of approximately1000, which alkenyl radical was a polymer of isobutene.

The base oil was an SAE 10 base oil.

The data were obtained in a Caterpillar L-l test under Mil-L-2104conditions for 120 hours.

The PD Nos. refer to the piston discoloration rating. After the enginetest, the three piston lands are examined visually. To a piston landwhich is completely black is assigned a PD number of 800; to one whichis completely clean, a PD number of to those intermediate betweencompletely black and completely clean are assigned PD numbersintermediate in proportion to the extent and degree of darkening.

The GD Nos. refer to the percentage deposits in the piston ring grooves;an 0 evaluation being a clean groove;

and a number of 100 being a groove full of deposits.

Table III hereinbelow presents data showing the efiectiveness of thesealkenyl succinimides in inhibiting piston varnish formation. These testswere obtained in an FL-Z test, using a 6-cylinder Chevrolet engineoperating at 2500 r.p.m. for a period of 40 hours. This test is fullydescribed in a Coordinating Research Council Bulletin entitled ResearchTechnique for the Determination of the Efiects of Fuels and Lubricantson the Formation of Deposits During Moderate Temperature Operation(1948).

The piston varnish rating is a visual observation of the amount ofvarnish on a piston skirt, with 10 being the rating of a clean pistonand "0" the rating of a piston fully covered with black varnish. Thispiston varnish rating correlates with road performance.

The dithiophosphate was a zinc salt of a mixed dialkyl dithiophosphatewherein one of the alkyl radicals contained 4 carbon atoms and the otheralkyl radical contained 5 carbon atoms. The dithiophosphateconcentration is expressed as millimols per kilogram (i.e., mMJkg.)

of finished product.

TABLE III Additive C D E F G succinimide, Wt. percent 0. 0 1. 0 0.6 l l.6 2. 0 Dithiophosphate, mMJkg 0. 0 0. 0 13 18 18 Test Results:

Piston Varnish Rating 2. 5 6.2 6. 9 7. 0 7.7

The alkenyl radical of the succinimide was an isobutene polymer having amolecular weight of about 700.

It is readily seen from the data set forth hereinabove that lubricatingoil compositions containing the succinimides described herein aremarkedly eifective for the lubricating of internal combustion engines.

In addition to the dithiophosphates described hereinabove, lubricatingoil compositions containing the N-dialkylaminoalkyl alkenylsuccinimides. of this invention may also contain other detergents,viscosity index improving agents, rust inhibitors, oiliness agents,grease thickening agents, etc.

What is claimed is:

1. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity, and, in an amount to impart detergencythereto, an N-dialkylaminoalkyl monoalkenyl succinimide, wherein saidalkenyl radical contains from 30 to about 200 carbon atoms, and saiddialkylaminoalkyl radical contains no more than 10 carbon atoms.

2. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity, and, in an amount to impart detergencythereto, an N-dialkylamino- 75 2,638,450

alkyl monoalkenyl succinimide, wherein said alkenyl radical is a polymerof an olefin containing from 2 to 5 carbon atoms, which polymer has amolecular weight from about 400 to about 3000, and saiddialkylaminoalkyl radical contains from 3 to 10 carbon atoms.

3. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity, and, in an amount to impart detergencythereto, an N-dialkylaminoalkyl monoalkenyl succinimide, wherein saidalkenyl radical is a polymer of an olefin containing from 2 to 5 carbonatoms, which polymer has a molecular weight from about 900 to about1200, and said dialkylaminoalkyl radical containing from 3 to 10 carbonatoms.

4. A lubricating oil composition consisting essentially of an oil oflubricating viscosity and from 0.1% to by weight, of anN-dialkylarninoalkyl monoalkenyl succinimide wherein said alkenylradical contains from 30 to about 200 carbon atoms, and saiddialkylaminoalkyl radical contains from 3 to 10 carbon atoms.

5. A lubricatng oil composition comprising a major proportion of an oilof lubricating viscosity from 0.25%

to 5%, by weight, of an N-dialkylaminoalkyl monoalkenyl of an oil oflubricating viscosity, and from about 0.1% i

to about 80%, by weight, of an N-dialkylaminoalkyl monoalkenylsuccinimide of the formula:

0 R-CHC R I wherein R is a hydrocarbon radical derived from a polymer ofan olefin containing from 2 to 5 carbon atoms, said polymer having amolecular weight in the range of about 900 to about 1200, and R, R and Rare aliphatic hydrocarbon radicals containing a sum total of 3 to 10carbon atoms.

7. A lubricating oil composition comprising a major proportion of apetroleum lubricating oil, and from about 0.25% to about 5%, by weight,of an N-substituted monoalkenyl succinimide of the formula:

0 RCHC n \NR-N/ 52-0; R1

wherein R is a polymer of isobutene having a molecular weight of about1000, and R, R and R are aliphatic GET-C CH3 0 wherein R is a polymer ofan olefin containing 4 carbon atoms, said polymer having a molecularweight of about 1000.

References Cited in the file of this patent UNITED STATES PATENTS2,490,744 Trigg et al Dec. 6, 1949 Rocchini July 22, 1952- White May 12,1953 UNITED. STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N003,018,250 I Janua lfyw23 1962 I Robert G, Anderson et a1.

It '1: hereby certified that error appears in the above numbered atantrequiring. correction and that the said Letters Patent should read ascorrected below.

Column 1, line 45 strike out "fectiveness as detergents for dispersingthe precursors" and insert instead add to crankcase oils to reduce thisformation Signed and sealed this 5th day of June 1962;

(SEAL) Atteat:

ERNEST w. SWIDER L- LADD Atteating Officer Cominiaeioner of Patents

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OILOF LUBRICATING VISCOSITY, AND, IN AN AMOUNT TO IMPART DETERGENCYTHERETO, AN N-DIALKYLAMINOALKYL MONOALKENYL SUCCINIMIDE, WHEREIN SAIDALKENYL RADICAL CONTAINS FROM 30 TO ABOUT 200 CARBON ATOMS, AND SAIDDIALKYLAMINOALKYL RADICAL CONTAINS NO MORE THAN 10 CARBON ATOMS.